LA 3126 - Taxi Cab Scheme【DAG最小路径覆盖】

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题目链接：https://icpcarchive.ecs.baylor.edu/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=1127

DAG最小路径覆盖 = 点数 - 最大匹配数。

代码:

#include <stdio.h>#include <ctime>#include <math.h>#include <limits.h>#include <complex>#include <string>#include <functional>#include <iterator>#include <algorithm>#include <vector>#include <stack>#include <queue>#include <set>#include <map>#include <list>#include <bitset>#include <sstream>#include <iomanip>#include <fstream>#include <iostream>#include <ctime>#include <cmath>#include <cstring>#include <cstdio>#include <time.h>#include <ctype.h>#include <string.h>#include <assert.h>using namespace std;int n;int p[510][510];int book[510];int match[510];bool vis[510];bool dfs(int u){    for (int i = 1; i <= n; i++)    {        if (book[i] == 0 && p[u][i] == 1)        {            book[i] = 1;            if (match[i] == 0 || dfs(match[i]))            {                match[i] = u;                return true;            }        }    }    return false;}struct node{    int x1, y1, x2, y2;    int st, ed;}taxi[510];int get_dis(node a, node b){    return abs(a.x2 - b.x1) + abs(a.y2 - b.y1);}int main(){    int t;    scanf("%d", &t);    while (t--)    {        memset(p, 0, sizeof(p));        memset(match, 0, sizeof(match));        memset(vis, false, sizeof(vis));        scanf("%d", &n);        int a, b, c, d, e, f;        char s[10];        for (int i = 1;i <= n;i++)        {            scanf("%s %d %d %d %d", s, &c, &d, &e, &f);            a = (s[0] - '0') * 10 + (s[1] - '0');            b = (s[3] - '0') * 10 + (s[4] - '0');        //  printf("        %d %d %d %d %d %d\n", a, b, c, d, e, f);            taxi[i].st = a * 60 + b;            taxi[i].ed = taxi[i].st + abs(c - e) + abs(d - f);            taxi[i].x1 = c;            taxi[i].y1 = d;            taxi[i].x2 = e;            taxi[i].y2 = f;        }        for (int i = 1;i <= n;i++)            for (int j = 1;j <= n;j++)            {                if (taxi[i].ed + get_dis(taxi[i],taxi[j]) < taxi[j].st)                    p[i][j] = 1;            }        int ans = 0;        for (int i = 1; i <= n; i++)        {            memset(book, 0, sizeof(book));            if (dfs(i))                ans++;        }        printf("%d\n", n - ans);    }    return 0;}

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